ipad2 randomly locks after update to iOS 9.0.2

I updated my iPad2 about three weeks ago and since then it has been locking on its own when I'm running Netflix or Pinterest or Safari (basically any app). I have tried to usb connect with my laptop restore from iTunes, hoping to get it back, but that doesn't work. I have turned it off and waited before turning it back off. Sometimes the battery drains completely because it refuses to lock when I want it to. Please help.

It is discouraging to read that people who take their iPad to the Apple store are only told to trade in and upgrade their iPad.

My iPad2 was working just fine before this update.